On radical anions in elucidation of mechanisms of organic reactions

Radical anions have been used to investigate the role of electron transfer in nucleophilic reactions and to obtain reduction potentials of short-lived radicals. In the first type of investigation the radical anions have been used to establish the dependence of the rate of electron transfer from an outer-sphere electron donor to a given substrate, to establish the stereochemistry of a radical coupling with the substrate, and to find the entropy and enthalpy of activation of electron transfer reactions compared with polar reactions. The potentials of short-lived radicals have been obtained from the competition between coupling of a radical with a radical anion and the reduction of the radical by the radical anion. The potentials have been used to rationalize some reactions such as the occurrence of radicals in certain Grignard reactions and the photochemical pinacolization of benzophenone in 2-propanol.